The present disclosure relates to a counterweight arrangement for an internal combustion engine in a motor vehicle. The disclosure relates, furthermore, to a method for optimizing the vibration behavior in an internal combustion engine with three cylinders.
Counterweight arrangements of this type serve for reducing or preventing vibrations occurring in an internal combustion engine, which, in a three-cylinder engine, are exerted, particularly in the form of a pair of inertia forces, on the crankshaft by the first and the third cylinder.
DE 32 32 027 A1 discloses a counterweight arrangement for internal combustion engines with three cylinders, in which, on the one hand, a countershaft with compensating weights fastened rigidly at its two ends is provided, which rotates at the same rotational speed as the crankshaft and in a direction opposite to this, and in which, additionally, counterweights are fastened to both ends of the crankshaft in order to compensate the reciprocating or rotating masses.
FR 2 779 493 A1 discloses a crankshaft which has a plurality of cranks and, at one end, an inertia flywheel which in one region has a material clearance, in order to generate a first force (gravitational force) acting eccentrically from the counterweight, and in which is provided, spaced apart axially from the inertia flywheel, a region with additional material or additional mass, in order to generate a second force (gravitational force) acting eccentrically from the counterweight.
DE 44 43 707 A1 discloses a low-vibration three-cylinder in-line internal combustion engine, in which the cranks for the three pistons lie in a common plane, the cranks for the two outer pistons forming a crank angle of 180° with respect to the crank for the middle piston, and the dimensions of the middle piston corresponding to the sum of the dimensions of the outer pistons.
DE 102 45 376 A1 discloses a crankshaft for a three-cylinder in-line reciprocating-piston engine, in which, to reduce the bearing loads on the crankshaft bearings, only two compensating masses are provided, which form an angle of 180° and generate equal and opposite compensating forces, the compensation plane formed by the compensating forces forming an angle of 30° with the first crank.
In an internal combustion engine without a balancing shaft, however, the vibrations occurring are not reduced to a minimum by counterweights forming an angle of 30° respectively with the first and the third crank or with the first and the third cylinder, when, as is usually the case in a transversely installed drivetrain, the crankshaft axis does not coincide with the main axis of the inertia matrix of the drivetrain, that is to say when the inertia matrix has non-diagonal elements which are unequal to zero.